Many liquid systems, such as fuel systems for engines, utilize replaceable filters for filtering particulate out of the liquid system. Once the filter becomes spent, i.e. its serviceable life has been used, the filter is replaced by removing the old filter and replacing it with a new filter.
In many systems, such as fuel systems, it is beneficial to avoid entraining air into the liquid system to avoid a reduction in performance of the downstream engine. However, during replacement of the filters, the filters are typically empty and filled with air. Once the system is started, as fuel is pumped into the filter, this air can be forced through the rest of the system affecting the downstream components.
As such, steps to evacuate this air have been tried. For instance, in U.S. Pat. No. 7,147,110 to Clausen et al. includes a vent orifice in an end cap of the replaceable filter element which allows air that is trapped within the filter to be evacuated through the filter element and vented back to the fuel tank. Unfortunately, the vent orifice of Clausen is directly exposed to the dirty fuel side of the filter and can be easily clogged preventing the evacuation of air through the vent orifice.
The present invention relates to improved systems for facilitating venting air from a filter, such as at maintenance intervals.